JP6033814B2 - Control method and control apparatus for injection unit - Google Patents

Description

  The present invention relates to an injection unit control method and control device, and more specifically, a heating cylinder, a screw provided inside the heating cylinder so as to be able to be driven in a rotational direction and an axial direction, and the heating unit. The present invention relates to a method and a control device for an injection unit including an injection material supply device for supplying an injection material to a cylinder.

  As is conventionally known, an injection molding machine is generally composed of an injection unit and a mold clamping unit. The injection unit includes a heating cylinder, a screw provided inside the heating cylinder so as to be driven in the rotational direction and the axial direction, and the like. An injection material supply device is attached to the proximal end portion of the heating cylinder, an injection nozzle is attached to the distal end portion, and a band heater for heating is provided on the outer peripheral portion. On the other hand, the mold clamping unit is a fixed mold attached to the fixed platen, a movable mold attached to the movable platen, a mold clamping device for clamping the movable mold to the fixed die, etc. It is composed of Therefore, an injection molded product can be obtained as follows. That is, the injection material is supplied from the injection material supply device to the base end portion of the heating cylinder, and the screw is driven to rotate. Then, the injection material is melted by heat applied from the band heater, frictional heat generated when the screw is rotationally driven, shearing heat, and the like in the process of being sent forward, and accumulated in the measuring chamber in front of the heating cylinder. At this time, the screw is retracted by the pressure of the accumulated injection material or by pullback. When the weighing is finished, the screw is driven in the axial direction, and injection filling is performed from the injection nozzle into a cavity formed between the fixed side mold and the movable side mold. Waiting for cooling and solidification, the movable mold can be opened to obtain a molded product.

  By the way, as understood from the above description, when the screw is rotationally driven to plasticize the injection material, the inner peripheral surface of the heating cylinder is fixed, while the outer peripheral surface of the screw flight moves. A relative dynamic contact occurs between the two. Even if contact occurs, since the injection material has a lubricating effect like an oil film, metal contact does not occur when the injection material is sufficiently present in the heating cylinder. However, when the injection material decreases and the lubrication effect cannot be obtained, metal contact occurs between them, and the inner peripheral surface of the heating cylinder and the outer peripheral surface of the screw flight are damaged. Therefore, in order to solve the above-described problem of metal contact, Patent Documents 1 to 3 propose a screw rotation control method or control device for an injection molding machine.

JP 2009-166317 A JP-A-2005-14308 Japanese Patent Laid-Open No. 10-202708

  Patent Document 1 discloses that a resin pressure at a distal end portion of a heating cylinder is a predetermined value during a plasticizing process in which a screw in a heating cylinder is rotationally driven to send resin from a proximal end portion side to a distal end side resin reservoir. Describes a screw rotation control method in an injection molding machine that switches the screw rotation speed to the low speed mode when the screw retraction speed becomes lower than the predetermined value or when the screw retraction speed becomes lower than a predetermined value. Patent Document 2 discloses a screw rotation control method that stops the rotation of the screw when the average torque value of the screw rotation torque per predetermined time becomes equal to or less than a reference torque value during the plasticizing process. Have been described. Furthermore, according to Patent Document 3, in the operation of purging the resin in the heating cylinder of the injection molding machine, when the load force of the screw rotation becomes a predetermined value or less, the timer starts counting, and the timer sets the predetermined value. There has been proposed a control method for switching the screw rotation speed to a low predetermined value when the time is counted up.

  As described above, according to the control method proposed in Patent Document 1, the pressure of the molten resin in the front end of the heating cylinder or the measuring chamber is measured, or the speed of the screw moving backward by the molten resin pressure is measured. The state of the molten resin in the heating cylinder can be known. However, these values are measured after the metal contact between the heating cylinder and the screw has occurred or is about to occur because there is almost no resin in the heating cylinder. Even if the screw rotation speed is reduced based on the above, metal contact is inevitable. This is because the “burn-in phenomenon” due to oil draining occurs instantaneously. According to the invention described in Patent Document 2, since the rotation of the screw is stopped when the average torque value of the screw becomes equal to or less than the reference torque value, the screw is operated at a high speed while the heating cylinder and the screw are in metal contact. Only the effect of not rotating is obtained. The invention described in Patent Document 3 simply switches the screw to a low-speed rotation after the purge operation is completed, and does not cause damage due to metal contact due to the high-speed rotation.

As described above, the screw rotation control method in the conventional injection molding machine is one in which the screw is switched to low speed rotation or stopped after the metal contact between the heating cylinder and the screw has occurred or is occurring. So the problem of metal contact still remains. In addition, there are also disadvantages that require expensive measuring instruments such as the pressure of the molten resin, the retraction speed of the screw, and the torque value of the screw.
Therefore, an object of the present invention is to provide a screw control method and a control device for an injection unit that can solve the problem of metal contact between a heating cylinder and a screw at low cost. Another object of the present invention is to provide a screw control method and control device for an injection unit that can also carry out a heat retaining step in addition to the above object.

The above-mentioned object of the present invention is achieved by monitoring the stock state of the injection material in the injection material supply device, that is, the hopper with an inexpensive level sensor, and controlling the rotational speed of the screw. Specifically, the injection unit is composed of a heating cylinder provided with a heater on the outer periphery thereof, and a screw provided inside the heating cylinder so as to be able to be driven in a rotational direction and an axial direction. An injection material supply device is provided at the base end of the screw, but if the time during which the level of the injection material in the hopper has decreased to a predetermined value continues for a predetermined time, or if the level decreases to a predetermined value, the rotational speed of the screw Configured to drop. According to another invention, when the level does not recover to a predetermined value even after a predetermined time has elapsed, the screw is stopped and the heat generation temperature of the heater is changed to a low heat retention temperature to enter the heat retention process. The According to still another invention, a hopper device includes a hopper in which an injection material is temporarily stored, and a storage cylinder that is intermittently or continuously supplied from the hopper, and a lower end portion of the storage cylinder is a base of a heating cylinder. In the injection unit connected to the end, the level of the injection material is configured to be measured with a storage cylinder.

  Specifically, in order to achieve the above object, the invention according to claim 1 includes a heating cylinder and a screw provided in the heating cylinder so as to be capable of being driven in a rotational direction and an axial direction. An injection material supply device is provided at one end of the injection unit, and an injection unit provided with an injection nozzle at the other end is used to supply the injection material from the injection material supply device to the heating cylinder. When the screw is measured by rotating at a first rotational speed, when the level of the injection material in the injection material supply device falls to a predetermined value and a predetermined time elapses or falls to a predetermined value, the screw of the screw The rotation speed is configured to be switched to a second rotation speed that is slower than the first rotation speed.

The invention according to claim 2 comprises a heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in a rotational direction and an axial direction, and an injection material is supplied to one end of the heating cylinder. The apparatus uses an injection unit provided with an injection nozzle at the other end to supply the injection material from the injection material supply device to the heating cylinder and to rotate the screw at a first rotational speed. When the level of the injection material in the injection material supply device is lowered to a predetermined value and a predetermined time has elapsed or when the measurement is reduced to a predetermined value, the rotational speed of the screw is made higher than the first rotational speed. The second rotation speed is switched to a slower second rotation speed, and when the level of the injection material in the injection material supply device recovers to the predetermined value within a predetermined time, the rotation of the screw is changed to the second rotation speed. The invention according to claim 3 comprises a heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in a rotational direction and an axial direction. An injection material supply device is provided at one end of the injection unit, and an injection unit provided with an injection nozzle at the other end is used to supply the injection material from the injection material supply device to the heating cylinder. When the screw is measured by rotating at a first rotational speed, when the level of the injection material in the injection material supply device falls to a predetermined value and a predetermined time elapses or falls to a predetermined value, the screw of the screw The rotation speed is switched to a second rotation speed that is slower than the first rotation speed, and the level of the injection material in the injection material supply device is not changed even after a predetermined time has passed. As when not recovered, it stops the rotation of the screw, to implement the incubating process by switching the heating temperature of the heater provided on an outer peripheral portion of the heating cylinder to a low temperature heat retaining temperature, and claim 4 The invention according to claim 1 is the method according to any one of claims 1 to 3, wherein the injection material supply device supplies a hopper in which the injection material is temporarily stored, and supplies the injection material intermittently or continuously from the hopper. And a storage cylinder adapted to be supplied to the heating cylinder, the predetermined value of the injection material being configured to be detected at a level in the storage cylinder.

The invention according to claim 5 comprises a heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in a rotational direction and an axial direction, and an injection material is supplied to one end of the heating cylinder. The apparatus is provided with an injection nozzle at the other end, and the screw is driven to rotate, the injection material is supplied from the injection material supply device to the heating cylinder and measured, and the screw is driven in the axial direction. A control device for an injection unit adapted to inject a metered injection material,
The control device includes means for setting a first rotation speed of the screw and a second rotation speed that is slower than the first rotation speed, a timer means, and a level sensor. When measuring by rotating at a first rotational speed, the level sensor detects a predetermined level of the injection material in the injection material supply device and counts a predetermined time, or detects a predetermined level, The rotational speed of the screw is configured to be switched to the second rotational speed. The invention according to claim 6 comprises a heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in a rotational direction and an axial direction, and an injection material is supplied to one end of the heating cylinder. The apparatus is provided with an injection nozzle at the other end, and the screw is driven to rotate, the injection material is supplied from the injection material supply device to the heating cylinder and measured, and the screw is driven in the axial direction. A control device for an injection unit adapted to inject a metered injection material, the control device comprising a first rotation speed of the screw and a second rotation slower than the first rotation speed. A means for setting a speed, a timer means, and a level sensor, and when the screw is measured by rotating the screw at a first rotational speed, the level sensor detects the injection material in the injection material supply device. When a predetermined level is detected and a predetermined time is counted, or when a predetermined level is detected, the rotational speed of the screw is switched to the second rotational speed, and the predetermined level is maintained even if the predetermined time is counted thereafter. When not recovering, the rotation of the screw is stopped, and the heat generation temperature of the heater provided on the outer peripheral portion of the heating cylinder is switched to a low temperature keeping temperature.

As described above, according to the present invention, when the screw is rotationally driven at the first rotational speed and plasticized, the level of the injection material in the injection material supply device, that is, in the hopper is lowered to a predetermined value. When the time elapses or when the screw speed falls to a predetermined value, the screw rotation speed is switched from the first rotation speed to the second rotation speed that is slower than the first rotation speed. In other words, the injection material in the heating cylinder Since the screw is switched to a low speed in anticipation of starvation before it becomes starved, the metal contact between the heating cylinder and the screw can be prevented without losing time. can get. According to another invention, when the level of the injection material in the injection material supply device does not recover to the predetermined value even after a predetermined time has elapsed after that, the screw is stopped from rotating. In addition to the above effect, the heat generation temperature of the heater is switched to a low temperature retention temperature, and the heat retention process is performed. Therefore, in addition to the above effects, there is an effect that neither curing of the resin in the heating cylinder nor resin burning occurs.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows embodiment of this invention, The (a) is a front view which shows the whole by making a cross section partially, The (a) is a schematic diagram which expands embodiment of the vicinity of a storage cylinder, The ( (C) is a schematic view showing the second embodiment in the vicinity of the storage cylinder in an enlarged manner, and (d) is a front view showing another embodiment of the injection material supply device in a partial cross section.

  Embodiments of the present invention will be described below. The injection unit according to the present embodiment is roughly similar to a conventionally known injection unit, and schematically includes a heating cylinder 1 and a screw provided inside the heating cylinder 1 so as to be able to be driven in a rotational direction and an axial direction. 5, an injection material supply device 10 provided at one end of the heating cylinder 1, that is, a right base end in FIG. 1A, and a controller or control device 25. The heating cylinder 1 has a predetermined length in the axial direction, and a plurality of band heaters 2, 2,. Moreover, the other front-end | tip part becomes the measurement chamber 3, and the injection nozzle 4 is provided in the most advanced part.

  The screw 5 moves in the axial direction with respect to the fixed heating cylinder 1 during plasticization and injection, but temporarily corresponds to the heating cylinder 1 from the base end portion to the tip end portion, the feed portion P1, the first metering. Part P2 and second metering part P3. A backflow prevention ring 6 is provided at the tip of the second metering portion P3. The injection material supply device 10 described above is provided corresponding to the feed part P1, and the measuring chamber 3 is located in front of the second metering part P3. The outer peripheral surface of the flight of the screw 5 is inserted into the heating cylinder 1 so as to be in contact with the inner peripheral surface of the heating cylinder 1. Thus, the drive device 7 is driven in the rotational direction and the axial direction.

  According to the embodiment shown in FIG. 1A, the injection material supply apparatus 10 includes a hopper 11 positioned at the uppermost position in the drawing, an injection material supplier 12 below the hopper 11, and a deaeration unit 15 below the hopper 11. Further, it is composed of a storage cylinder 20 and the like below. And the lower end part of the storage cylinder 20 is opened inside the heating cylinder 1.

  The hopper 11 has a funnel shape as a whole, and the injection material is temporarily stored therein. As the injection material, in the present embodiment, a pellet or powdery synthetic resin, a granular shape, a flake shape or a crushed small piece shape, for example, a metal having a low melting point such as magnesium, aluminum, zinc, tin, or the like It is intended for alloys. The injection material supplier 12 has an effect of intermittently supplying the injection material in the hopper 11 to the storage cylinder 20 by gravity, and a rotation supply rotor 13 having a pocket is provided therein. Since the injection material is intermittently dropped and supplied by the rotation of the rotor, the occurrence of crosslinking is suppressed by the vibration. Or the deaeration effect is enhanced.

  The deaeration unit 15 is for exhausting air contained in the injection material supplied from the injection material supplier 12 to the storage cylinder 20 and has an intake chamber 16 having a relatively large diameter. A cylindrical guide member 17 for guiding the falling injection material to the next storage cylinder 20 is provided inside the intake chamber 16, and a communication pipe 18 is connected to the side portion. The communication pipe 18 communicates with the vacuum source P through the filter 19.

  The storage cylinder 20 is at least partially made of a transparent material, and the level of the internal injection material is measured or detected from the outside. The level sensor 21 includes a laser light sensor, a near-infrared sensor, and the like. In the embodiment shown in FIGS. 1A and 1B, one of the level sensors 21 is a storage cylinder 20 as in the conventional injection unit. Is provided at a predetermined position, for example, a relatively high position. When this one level sensor 21 detects that the injection material has been lowered to the position of the sensor, the rotation supply rotor 13 rotates by a predetermined number of revolutions and is supplied to a predetermined height in the storage cylinder 20. When plasticization or molding progresses and it is detected that the injection material has been lowered to the position of the level sensor 21, the rotation supply rotor 13 is again rotated by a predetermined number of revolutions and supplied. Thereafter, similarly, a predetermined amount of the injection material in the storage cylinder 20 is maintained. According to this embodiment, the above-described level sensor 21 provided in the conventional injection unit is shared, and the rotational speed of the screw 5 is controlled simply by changing or adding software. The device has the feature that it does not cost. In the present embodiment, on / off detection is performed in which the level sensor 21 detects whether or not the injection material has fallen to a predetermined level.

  The control device 25 has a general control function necessary when injection molding is performed using the above-described injection unit, and also has the following functions specific to the present embodiment. It also has setting means and timer functions unique to this embodiment. The control device 25 having such functions and setting means is connected to the level sensor 21 by a signal line a, to the screw drive device 7 by a signal line b, and to the band heater 2 by a signal line c. Yes.

  Next, the operation will be described. The amount of the injection material in the storage cylinder 20 is controlled by one conventional level sensor 21 as described above. A first rotational speed S1 of the screw 5 during normal plasticization and a second rotational speed S2 that is slower than this are set in the control device 25. As the second rotational speed S2, for example, a rotational peripheral speed of 30 m / min of the screw 5 is set. The first set time after the level sensor 21 detects that there is no injection material, in other words, the first predetermined time T1 after detecting that the injection material has dropped to a predetermined value, this first time. A second predetermined time T2 that is later than the predetermined time T1 is set. Further, the heat generation temperature of the heaters 2, 2,.

  Then plasticize or weigh as follows. That is, the screw drive device 7 rotates the screw 5 at the first rotational speed S1. The injection material in the storage cylinder 20 is supplied to the heating cylinder 1 corresponding to the feed part P1 of the screw 5. The injection material is sequentially fed to the feed part P1, the first metering part P2, the second metering part P3, and friction heat, shear heat, band heaters 2, 2,. It is melted by the heat applied from above and is fed to the measuring chamber 3 by pressure. The screw 5 is retracted by the pressure of the molten resin in the measuring chamber 3. Alternatively, force back suck. When a predetermined amount is measured, the screw 5 is driven in the axial direction and injected from the injection nozzle 4 to the mold to obtain a molded product.

  When the level sensor 21 detects a predetermined value when the screw 5 is plasticized at the first rotational speed S1 as described above, the signal is input to the control device 25, and the control device 25 is based on the signal. When the level recovers within the first predetermined time T1 including the time measurement, the level returns to the initial state. In addition, even if it recovers within 1st predetermined time T1, it can also implement so that it may switch to 2nd rotational speed S2 for safety.

  When the level is recovered within the second set time T2 after the screw 5 starts to be driven at the second rotation speed S2, the screw speed is returned to the first rotation speed (S1). If the level does not recover to the predetermined value even after the second predetermined time T2 has elapsed since the start of driving at the second rotational speed S2, a screw stop (S0) signal is output from the control device 25. At the same time, the heat generation temperature of the heaters 2, 2,... Is controlled to a low heat retention temperature, and the heat retention process is started. The relationship between the rotational speed (S1, S2, S0) of the screw 5 and the predetermined time (T1, T2) as described above is shown in FIG.

  According to this embodiment, when the level of the injection material in the storage cylinder 20 reaches a predetermined value and a predetermined time has passed, the rotational speed of the screw 5 is reduced before the heating cylinder 1 becomes starved. Metal contact due to lack of material does not occur. If the level does not recover even after a predetermined time has elapsed, not only the screw is stopped but also the heat generation temperature of the band heaters 2, 2,... However, the resin does not harden in the heating cylinder 1 and does not cause resin burning.

  The above embodiment uses the level sensor 21 originally provided in the injection unit, but a second embodiment provided specially is shown in FIG. Like the conventional injection unit, the storage cylinder 20 is provided with one level sensor 21a or two level sensors 21a and 21b above and below, and the level of the injection material in the storage cylinder 20 is determined by these sensors 21a or 21b. It is controlled as described above. In such an injection unit, according to the second embodiment, a level sensor 21 'for detecting an abnormal value or a predetermined value is provided below the level sensor 21b. When the level sensor 21 'detects a predetermined value set in the control device 25, the screw 5 is immediately switched to the second rotational speed (S2). When the level is recovered within the predetermined time T2 after switching, the screw 5 is returned to the first rotational speed (S1), and when the predetermined time (T2) has not elapsed, the screw 5 stops (S0). In the same manner, the heat retaining step is entered. It is obvious that the same effect can be obtained by increasing the level sensor 21 'by one in this embodiment.

  FIG. 1D shows another embodiment of the injection material supply apparatus. The injection material supply device 10 shown in FIG. 1A is composed of a rotary supply rotor 13 having a pocket, so that the supply by the pocket is intermittent, but it is shown in FIG. Since the injection material supply device 10 'is composed of a screw feeder 13', the supply is continuous. Similar members will be given the same reference numerals with a dash “′” and will not be described repeatedly, but it is clear that similar actions or effects can be obtained. Moreover, it can replace with screw feeder 13 'and can also be implemented with a rotary feeder.

DESCRIPTION OF SYMBOLS 1 Heating cylinder 2 Band heater 5 Screw 7 Screw drive apparatus 10 Injection material supply apparatus 11 Hopper 20 Storage cylinder 21 Level sensor 21 'Level sensor S1 1st rotation speed of a screw S2 2nd rotation speed (1st rotation) of a screw Slower than speed)
T1 First setting or predetermined time T2 Second setting or predetermined time (slower than the first predetermined time)

Claims (6)

A heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in the rotational direction and the axial direction. An injection material supply device is provided at one end of the heating cylinder and an injection is provided at the other end. Using an injection unit provided with a nozzle, the injection material is supplied from the injection material supply device to the heating cylinder, and the screw is rotationally driven at a first rotational speed (S1) and measured. When
When the level of the injection material in the injection material supply device falls to a predetermined value and a predetermined time (T1) elapses or falls to a predetermined value, the rotational speed of the screw is slower than the first rotational speed (S1). Switching to the second rotation speed (S2), the injection unit control method A heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in the rotational direction and the axial direction. An injection material supply device is provided at one end of the heating cylinder and an injection is provided at the other end. Using an injection unit provided with a nozzle, the injection material is supplied from the injection material supply device to the heating cylinder, and the screw is rotationally driven at a first rotational speed (S1) and measured. When
When the level of the injection material in the injection material supply device falls to a predetermined value and a predetermined time (T1) elapses or falls to a predetermined value, the rotational speed of the screw is slower than the first rotational speed (S1). While switching to the second rotation speed (S2), and when the level of the injection material in the injection material supply device recovers to the predetermined value within a predetermined time (T2), the rotation of the screw is changed to the first rotation speed. Returning to (S1), the control method of the injection unit characterized by the above-mentioned. A heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in the rotational direction and the axial direction. An injection material supply device is provided at one end of the heating cylinder and an injection is provided at the other end. Using an injection unit provided with a nozzle, the injection material is supplied from the injection material supply device to the heating cylinder, and the screw is rotationally driven at a first rotational speed (S1) and measured. When
When the level of the injection material in the injection material supply device falls to a predetermined value and a predetermined time (T1) elapses or falls to a predetermined value, the rotational speed of the screw is slower than the first rotational speed (S1). When the level is changed to the second rotational speed (S2) and the level of the injection material in the injection material supply device does not recover to the predetermined value even after a predetermined time (T2) has elapsed thereafter, the rotation of the screw is stopped. And (S0) and switching the heating temperature of the heater provided on the outer peripheral portion of the heating cylinder to a low temperature holding temperature to carry out the temperature holding process. The method according to any one of claims 1 to 3, wherein the injection material supply device is a hopper in which the injection material is temporarily stored, and is intermittently or continuously supplied from the hopper, and the heating cylinder. A control method for an injection unit, comprising: a storage cylinder supplied to the storage cylinder, wherein a predetermined value of the injection material is detected at a level in the storage cylinder. A heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in the rotational direction and the axial direction. An injection material supply device is provided at one end of the heating cylinder and an injection is provided at the other end. A nozzle is provided, and the screw is driven to rotate, and the injection material is supplied from the injection material supply device to the heating cylinder and measured, and the screw is driven in the axial direction to inject the measured injection material. A control device for the injection unit,
The control device includes means for setting a first rotation speed (S1) of the screw and a second rotation speed (S2) lower than the first rotation speed, a timer means, a level sensor (21 )
When the screw is rotated and measured at the first rotational speed (S1) and measured, the level sensor (21) detects a predetermined level (L) of the injection material in the injection material supply device and detects a predetermined time ( When the time T1) is measured or a predetermined level is detected, the screw rotation speed is switched to the second rotation speed (S2). A heating cylinder and a screw provided in the heating cylinder so as to be able to be driven in the rotational direction and the axial direction. An injection material supply device is provided at one end of the heating cylinder and an injection is provided at the other end. A nozzle is provided, and the screw is driven to rotate, and the injection material is supplied from the injection material supply device to the heating cylinder and measured, and the screw is driven in the axial direction to inject the measured injection material. A control device for the injection unit,
The control device includes means for setting a first rotation speed (S1) of the screw and a second rotation speed (S2) lower than the first rotation speed, a timer means, a level sensor (21 )
When the screw is rotated and measured at the first rotational speed (S1) and measured, the level sensor (21) detects a predetermined level (L) of the injection material in the injection material supply device and detects a predetermined time ( When T1) is timed or when a predetermined level is detected, the rotational speed of the screw is switched to the second rotational speed (S2), and then recovered to the predetermined level even if the predetermined time (T2) is further counted. When not, the injection unit control device stops rotation of the screw and switches the heat generation temperature of the heater provided on the outer peripheral portion of the heating cylinder to a low temperature keeping temperature.

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